Switch-operating mechanism interlock



April 6, 1954 v H. M. STlEGLlTZ 2,674,666

SWITCH-OPERATING MECHANISM INTERLOCK Filed April 24, 1952 3 Sheets-Sheet l INVENTOR. H E N R Y M. sT/e'ez/rz A T'TORNEYS April 6, 1954 H. M, STIEGLITZ 2,674,656

SWITCH-OPERATING MECHANISM INTERLOCK Filed April 24, 1952 3 Sheets-Sheet 2 INVENTOR. hf/VRY M 677561172 ATTORNEYS.

April 6, 1954 H. M. STIEGLITZ 2,574,666

SWITCH-OPERATING MECHANISM INTERLOCK Filed April 24, 1952 5 Sheets-Sheet 3 INVENTOR, HENRY M. STIEGL/TZ A TTORNEYS.

Patented Apr. 6, 1954 UNITED STATES PATENT OFF ICE SWITCH-OPERATING MECHANISM INTERLOCK.

Henry M. Stieglitz, St. Louis, Mo., assignorto Frank Adam'Elect-rie Company, St. Louis, Mo., a corporation of-Missouri Application April-.24, 1952, Serial No. 284,009

13 Claims. 1

This invention relates to switch-operating mechanism for enclosed. switch gear, and more particularly to switch-operating mechanism for. correlatingmanipulation of a switch-handle with anaccess door.

Electric power circuits of'large capacity are commonly protectedby an enclosed fused'switch, examples of which. are disclosed in UnitedStates Patents Nos. 2,332,633, and 2,450,705; Such devices generally. include fuse holders accessible througha door. in thefront of the enclosure and switch contacts actuated by an exterior switch lever. There may also be a door interlock device operated by the switch lever for preventing an uninformed person from opening the door withoutfirst opening the switch. It is an object of: this invention to provide in such devices improved switch-actuating and door-interlock mechanism.

In particular, it is desired to provide for movement of theswitch leverin a plane parallel to the front face of the enclosure from. a circuitclosed position blocking the door to a circuit-open position clear. of the door, which switch-lever. movement offers certain advantages over prior devices of this generaltype.

Another object of this invention is the provision of a rugged, inexpensive, non-jamming in: terlock mechanism.

A further object of this invention is the provision of suchinterlock mechanism wherein the door may be unlatched without opening of. the circuit, but by. a. technique which. is unobvious to-uninformed persons. It is contemplatedthat a skilled technician may-have occasionto open the door without opening the circuit, and the insterlock mechanism-of thisinvention isadapted to-permit such opening ofthe access door, by atechniquethat will be known only by the skilled technician.

Inaccomplishing these objectives, I provide an overscentering. mechanism for imparting. snap.- action .to the switchcontacts. The over-centering mechanism isoperatedfrom acrossbar movabletransversely of itself between circuit-open and.circuit-closed.positions. The switch handle is fixedon a shaft extending through the frontof the enclosure. and this shaft. carries a combination switch-actuating and door-interlocking cam. Apairof spaced posts are arranged to roject: fromthe'cam and; straddle the crossbar so that* the. over-centering mechanism is actuated upon manipulation of" the switchhandler This cam is also. formediabout a part of. its periphery forlocking cooperation with a latch member. that 3 is movable into and out of latching engagement wih the door.

Other features of the invention will be in part apparent and in part pointed out in thefollowing detail description taken in conjunction withthe accompanying drawings in which:

Fig. 1 is an oblique view taken from the outside of the enclosed switch gear of this invention;

Fig. 2 is an oblique view of certain mechanism within theswitch enclosure of Fig. 1;

Fig. 3 is an end view of theenclosed switch gear with the switch handle in circuit-open position;

Fig. 4. is a longitudinal section taken on the line 44' of Fig. 3,.showing positions of parts for an open-circuit condition;

Fig. 5 is a view similar to that of'Fig. 4 showing positions of parts for a closed-circuit condition;

Fig. 6 is an enlarged view taken from within the enclosure toward the front panel thereof showing positions of parts for a circuit-closed condition;

Fig. '7v is a View similar to that of Fig. 6 showing positions of partsfor a circuit-open condition, with dotted and dashed lines showing alternative ositions of a latch member; and,

Fig. 8is av view similar to that of Fig. 6 showing parts-in position for opening the door without openingthe circuit.

Referring to Figs. 1,2 and 3 of the drawings, there is shown an operating mechanism for a suitableswitch (not shown) housed within an openeended enclosure 2. The enclosure 2 is formed with a front panel 3, channel-shaped side panels 5 and a rear, panel]. On the rear panel I there is mounted one or more switches (not shown) which may includefuse holders, the detail'sof-which do not form a partof this invention but which are shown, for example, in United States Patent No..2,310,9l8. The fuse holders generally face toward the front of the housing in the center portion thereof, and a door 9' is hinged at lilonthe front. panel 3 so that fuses may readily be replaced. A crank H is journaled at its ends I in the side walls- 5 to extend across the back 'lof the enclosure for-actuating cooperation with-the switch contacts.

In accordance with this invention, the-circuit is controlled by an exterior switch handleor lever" I3 which is'mounted for rotary movement in a plane parallel: to the front-face 3- of the enclosure adjacent the door 91 The handle [3 is arranged to swing with snap-action between a circuit-closed position wherein the handle ex,- tends: across'the door- (Figs. 5 and: 6) and a circult-open position wherein the handle extends clear of the door (Figs. 4 and '7). Latching mechanism I5 is also operated by the switch handle 13 to provide for safety interlock against opening of the door with the circuit closed.

Snap-action is imparted to the switch contacts by means of a lost-motion over-centering mechanism ll located at the sides 5 of the enclosure and adapted for coupling the switch-operating handle I3 to the crank H. Thi over-centering mechanism ll comprises crank-actuating plates [9 pivoted on the ends I of the crank ll, one at each side of the enclosure. Each plate I9 has a pair of spaced crank-actuating lugs. A lug 2! is adapted to throw the crank I I to circuit-closed position (Fig. 5) and a lug 23 is adapted to throw the crank to circuit-open position (Fig. 4). Each plate further has 2. lug 25 received within a bearing 28 formed at one end of an over-centering spring operator N, the other end of which is received through a support 29 fixed to the adjacent side 5 of the enclosure.

The crank-actuating plates [9 are swung between alternative circuit-open and circuit-closed positions by associated links 3|. Each link 31 is formed at one end with a lug 33, which is received through an aperture 35 of the associated plate [9. The other end of the link has a lug 3'! received through an aperture 39 in an arm of a U-shaped member 4! which is pivoted at 42 on the side panels 5. A crossbar 43 of the member 4| extends across the enclosure beneath the front panel 3 and adjacent the handle [3.

The switch handle I3 is fixed upon the outer end of a shaft 45, which itself is rotary in a sleeve 41 that projects from the outer faces of the front panel 3 and which carries a cam plate 49. This cam plate has depending posts 5! spaced apart to straddle the crossbar 43, so that the cam 49 is effective to swing the member ll toward and away from the over-centering mechanism l1 upon manipulation of the handle.

The cam plate 49 also forms a part of the interlock mechanism l5. As best shown in Figs. 6 to 8, the cam has an edge 53 shaped to act as a stop for a latch plate 55, and the latch plate 55 is pivoted at 5'! on the panel 3 for movement into and out of latching engagement with the door 9. More particularly, a wedge-shaped latch hook 59 is secured on the door at the edge opposite its hinge [0 for cooperation with a projecting latching lug SI of the latch. plate. Movement of the latching lug 6| relative to the hook 59 is limited by a stop lug 53 formed on the latch plate for abutting cooperation with the edge 53 of the cam plate.

The cooperating edges of latching lug BI and latch hooir. 59 are so configurated (as seen in Figs. 2 and 3) that outward pull on knob 59 tends to rock plate 55 about its pivot 51 in a direction which disengages the latching parts 59 and GI. Such rocking of plate 55 is, however, prevented by engagement of stop lug '53 with edge 53, when the parts are in the closed-circuit position. It will be noticed that lug 'GI is located relatively close to the pivot 51 as compared with the location of the stop lug 93, so that although the lug 63 may normally be spaced from the cam edge 53 to permit free rotation of the cam, yet the lug 63 will engage the cam edge when attempt is made to open the door with the cam in the circuitclosed position of Fig. 6.

Release of the latch is permitted upon rotation of the cam 49 by the switch handle [3 to a position such that edge 53 no longer prevents rocking of.

plate 55 about its pivot 51. For example, in the open-circuit position of Fig. 7, a recessed edge portion 55 of the cam aligns with the stop lug 63. The stop lug 53 may then move into the recess 55 to free the latch part 5| of the latch hook 59 as indicated by the dotted lines of Fig. 7. The latch plate 55 is normally biased into latching engagement with the hook 59 by a coil spring 61. This spring 61 is secured at one end '56 upon the latch plate and at its other end upon a door-stop strip '68 of the enclosure.

A pawl lug 69 is also formed on the latch plate for engagement with the cam when the door is opened. This pawl 69 cooperates with a ratchet notch 1| formed on the cam for the purpose of preventing closing of the circuit when the door 9 is opened with the cam 49 in the position of Fig. '7. Upon opening of the door, the latch plate 55 is released at El and the spring 6'! biases the pawl lug 59 into engagement with the cam surface 53, the cam then being in the position 01' Fig. 7 and the cam itself is rotated counterclockwise by a hairpin spring 15 to seat the pawl 59 in the ratchet notch "ll (dashed lines of Fig. '7). The spring 15 has one end secured in the strip 68 and its other end is hooked over the recessed edge portion 55 of the cam at 16. The pawl then prevents rotation of the switch handle 13 to its circuit-closed position unless the pawl 69 is first retracted either upon manipulation of the latch plate by an informed person or by the cooperation of the elements 59 and BI upon reclosure of the door.

The over-centering mechanism l1 drives the parts either to their circuit-open or circuit-closed positions, so that in normal operation, the circuit would be opened in order to gain access to the fuses. There may be occasions, however, when it is desired to open the door 9 without opening the circuit, and this may be accomplished with the switch mechanism of this invention. Referring to Fig. 8., it will be noted the cam 49 has a small notch 7! in its periphery adjacent the recess 55. The position of this notch 11 is coordinated with the lost motion in the over-centering mechanism l1 and with the positioning of the switch handle l3 relative to the door, in such manner that the notch Ti will align with the stop lug 63 upon rotation of the switch handle an amount sufiicient to clear the door 9 yet insuflicient to throw the crank-actuating plates l9 over center and open the switch.

When the handle is positioned thus, the overcentering springs 26 exert a considerable bias upon the parts including the handle, and the handle barely clears the door, hence it is not apparent to the uninitiated that the door could be opened with the handle manipulated in this manner. A skilled technician competent to work on live equipment, however, may be properly'informed or this feature. When the cam 49 is positioned as shown in Fig. 8 and the door opened, the stop lug 63 moves into the notch 11 to clear the latch elements 59 and BI. The

-- ratchet notch 1| does not then receive the pawl 69, their relative positions being shown in Fig. 8. hence the handle l3 may be released to return to its circuit-closed position to indicate a closedcircuit condition.

From the above, it will be noticed that the switch-operating mechanism of this invention provides an improved switch-handle movement whereby the position or the handle relative to the access door serves as an indication of the circuit condition and as an indication that the circuit: shouldtbe .opened :priorto; op ningxoir he access-. door: Additionally. this correlation: oi doonand-gswitch-handle movement-to ether with thezjover-centering actiontends to prevent undesired openingxoffthe access door withuthe. circuit closed, since. the special;- manipulation discussed above; is thereby rendered; inconvenient. Moreoverrshouldxthe'door be opened with the switch closed. eitherrby the-above technique-or by man: ual. manipulation of-the latch plate, the doorhand'le swings across the. door opening to. prevent reclosure: of the door without .first adjusting the mechanismthereby avoiding possibility of jamming the mechanism, aswas possiblezwith prior switchgear of this general type.

The parts'themselvesn are relatively fewcone sidering the various features provided, and; the construction is rugged and troublefree. More.- over; the. mechanism Oflflflis invention is adapted for use iniconjunction withmany types of'prior switch gear. For, example, the over-centering mechanism and the. U -shaped bracket. arrange.- ment is, to some extent, standardand the switch operating herein disclosed may readily be used with such standard parts.

From the foregoing description, it is apparent thatath'ose skilled'in the art will understandthe structure, function and mode of operation of'the invention herein disclosed and appreciate the-advantages thereof. Although one embodiment has been disclosed in detail, it is to be understood that the inventionis not limitedthereto, but the drawings and description thereof are tO'be understood as being merely illustrative. It is realizedthat many modification and variations will present themselves to those skilled in the art without: departing from'the'spirit of this invention or. the scope thereof as set forth in the appendedclaims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patentis-z 1. In enclosed switch gear. having a front panel provided with an access door; an exterior switch-operating lever mounted on the front panel forrotation in a, plane parallel thereto from a circuit-closed position across the door to a circuit-open'position'clear ofthedoor, and interior door-latch means including a part rotary with the switch=operatingileuerfor lockingthe door when the lever is in its circuit-closed position and for unlocking the door when the switch lever is moved to its circuit-open position.

2. In enclosed switch gear having a front panel provided with an access door; an exterior switch-operating lever mounted on the front panel for rotation in a plane parallel thereto from a circuit-closed position across the door to a circuit-open position clear of the door, an interior cam driven by the switch-operating lever for movement between circuit-closed and circuitopen positions, and cam-locked latch means movable into and out of latching engagement with the door, said cam being shaped to lock the latch means in circuit-closed position and to release the latch means in circuit-open position.

3. In enclosed switch gear having a front panel provided with an access door; an exterior switch-operating lever mounted on the front panel for rotation in a plane parallel thereto from a circuit-closed position across the door to a circuit-open position clear of the door, an interior cam driven by the switch-operating lever for movement between circuit-closed and circuitopen positions, and a movable latch member snrinsebiesedfinto latchine-rensa ement-sw1 h:the doorrsaid door having a wedge-shaped hoolefe retracting-the latch member upon opening-orrthe door, and said cam being shaped to lock'the latch means against retraction in circuit-closedDosi-r tion. and to release the latchmeans for retrace tion in circuit-open position.

4. In enclosed switch gear: having a. front panel provided with a hinged access, door; switchactuating mechanism' including. an interior switch-actuating member arranged to be moved between circuit-open and circuit-closed positions, a:.rota-ry-shaft member extending through said paneladjacent said switch-actuating member, a cam carried on the inner end of :said .shaft mem-.. ber and having driving means offset from them-- taryaxisof the camaarranged for actuating cooperation with said switch-actuating member uponrotation of the cam between circuit-open and circuit-closed positions, and a switch-handle carried on the outer end of said shaft'member;

5: Enclosed switch gear as set forth inclaim 4 further including a movable latch member spring-biased into latching engagement with the door, said door having a wedge-shaped hook for retracting the latch upon the application of opening force to the door, and said'cam'being shaped to lock th latch member against retractioni-n its circuit-closed position and release-the latch member forretraction by the hook-when'ln its circuit-open position.

6; Enclosedswitch gear as setforthin claimd further including a latch plate pivoted on said front panel adjacent said cam and having a stop lug, said latch plate having a latching lug movable into andout of latching engagement with the door, and said cam being formed about its periphery with a portion engageable with said stop lug for limiting movement of the latch plate when the cam plate is in circuit-closed position and with a recessed portion adapted to receive said stop lug to'permit movement of said latch plate upon rotationof the cam to its circuit-open position.

*7. Enclosed switch gear-asset forth in claim 6 wherein the latchplatefurther includes a pawl lug and spring means on the plate for biasingthe pawl lug into engagement with the edge of said cam, the pawl'being' retained in a-retracted position by the latching lug when the dooris closed and being released when the door is opened, and said cam being formed with a ratchet notch adapted to receive said pawl lug when the cam is rotated to its circuit-open position, thereby to prevent rotation of the switch handle from its circuit-open position when the door is open.

8. Enclosed switch gear as set forth in claim 7 wherein the door has a wedge-shaped member projecting therefrom for cooperation with the latching lug on the latch plate, said wedgeshaped member being shaped to rotate the latch plate against its bias and withdraw the pawl lug from said ratchet notch upon reclosure of the door.

9. In enclosed switch gear having a front panel provided with a hinged access door; switch-actuating mechanism including a springbiased over-centering device and an interior switch-actuating member adapted to be moved between circuit-open and circuit-closed positions, a rotary shaft member extending through said front panel adjacent said switch-actuating member, a cam plate carried on the inner end of said shaft member and having driving means oflset from the rotary axis of the cam plate for actuating cooperation with said switch-actuating member, the switch-actuating member thereby being actuated against the bias of the overeentering device between circuit-open and circuit-closed positions upon rotation of the cam plate, a switch handle secured to the outer end of said rotary shaft, and a latch member movable into and out of locking engagement with the door, said cam plate being shaped to lock the latch member in circuit-closed position and to unlock the latch member when the cam plate is rotated against bias from circuit-closed position and prior to over-centering of the switchactuating mechanism.

10. In enclosed switch gear having a front panel provided with a hinged access door; switchactuating mechanism including an over-centering device and an interior switch-actuating member adapted to be moved between circuitopen and circuit-closed positions, a rotary shaft member extending through the front panel, a cam carried on the inner end of said shaft member and having driving means offset from the rotary axis for cooperation with said switchactuating member, the cam thereby being biased by the over-centering device to circuit-open or circuit-closed positions, a switch handle secured to the outer end of said rotary shaft for rotation with the shaft in a plane parallel to the front panel from a circuit-closed position across the door to a circuit-open position clear of the door, a movable latch member spring-biased into latching engagement with the door, said door having a wedge-shaped hook for retracting the latch upon opening of the door and said cam being shaped to lock the latch member against retraction when in its circuit-closed position and to release the latch for retraction when in its circuit-open position.

11. Enclosed switch gear as set forth in claim 10 wherein said cam further includes notched means adapted to release the latch member for retraction when the cam and the switch handle are rotated an amount sufficient to clear the door but insufficient to over-center the switchactuating mechanism.

12. In enclosed switch gear having a front panel and a hinged access door therein; switchactuating mechanism including an over-centering device and a crossbar adapted to be moved transversely of itself against the bias of the overcentering device between circuit-open and circuit-closed positions, a rotary shaft extending through the front panel, a cam plate secured to the inner end of said shaft, said cam plate having post means offset from the rotary axis of the cam plate and straddling said crossbar, the cam plate thereby being biased by the overcentering mechanism to circuit-open or circuitclosed positions, and a switch handle secured to the outer end of said rotary shaft for rotation with the cam in a plane parallel to the front panel from a circuit-closed position across the door to a circuit-open position clear of the door. 13. In enclosed switch gear having a front panel and a hinged access door therein; switchactuating mechanism including an over-centering device and a crossbar adapted to be moved transversely of itself against the bias of the overcentering device between circuit-open and circuit-closed positions, a rotary shaft extending through the front panel, a cam plate secured to the inner end of said shaft, said cam plate having post means offset from the rotary axis of the cam plate and straddling said crossbar, the cam plate thereby being biased by the over-centering mechanism to circuit-open or circuit-closed positions, a switch handle secured to the outer end of said rotary shaft for rotation with the cam in a plane parallel to the front panel from a. circuit-closed position across the door to a circuit-open position clear of the door, and a movable latch plate adapted for cooperation with an edge of the cam plate, said latch plate being biased into latching engagement with the door and being retractable out of latching engagement with the door, and said cam plate being formed about its periphery with a portion adapted to limit movement of the latch plate when the cam is in its circuit-closed position.

References Cited in the file of this patent UNITED STATES PATENTS Australia Jan. 28, 1938 

